Added max_mem_abs and min_mem_abs to ResourceWatcher
Added human2bytes to utils.py
Added test for max and min abs mem of ResourceWatcher
Added documentation for max and min abs mem of ResourceWatcher
Merge remote-tracking branch 'upstream/master' into ressource-watcher-mem-abs

Conflicts:
	circus/plugins/resource_watcher.py
	circus/tests/test_plugin_resource_watcher.py
	docs/source/for-ops/using-plugins.rst
Fixed flake8 warnings, adpated tests to async architecture
Added use_working_dir and watchers to CircusPlugin, missing tests
Removed useless backslashes
Merged max_mem_abs and max_mem (same for min)
Rewrote util.human2bytes + unit tests
fixed doc
Fixed if syntax
Merge remote-tracking branch 'origin/ressource-watcher-mem-abs' into ressource-watcher-per-process
Added per_process and use_reload + doc
Upgraded use_reload to action, needs doc and tests
pid must be an integer and casted accordingly
Merge branch 'fix-signal-command-pid-type' into ressource-watcher-per-process
Added use_reload to plugin CommandReloader
Fixed restart loops
Avoid multiple restarts
Fixing mistakes